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Introduction to PHP and Server Side Technology

Introduction to PHP and Server Side Technology

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Introduction to PHP and Server Side Technology

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  1. Introduction to PHP and Server Side Technology

  2. PHP History • Created in 1995 • PHP 5.0 is the current version • It’s been around since 2004

  3. General PHP Characteristics • PHP is made up of a PHP scripting block • PHP scripting blocks can appear anywhere in a Web page • In addition to PHP scripting blocks, PHP documents typically contain XHTML • A page having embedded PHP script must have a file suffix of .php

  4. The Basics of PHP Syntax • PHP script always appears between • <?php and ?> • PHP statements always end in a semi-colon • Comments have the same format as JavaScript • PHP IS CASE SENSITIVE

  5. A First PHP Program • As in • <html> <body><?phpecho "Hello";?> </body></html>

  6. A First Server Round Trip Using Forms (1) • Remember form widgets from JavaScript <input type=“text”> and so on • Remember widgets are contained in a form • Widgets are visible from PHP script so we can process their contents to the server

  7. A First Server Round Trip Using Forms (2) • The following form posts to the page named Welcome.php (action attribute) <form action="welcome.php" method="post"> Name: <input type="text" name="fname" /> Age: <input type="text" name="age" /> <input type="submit" /> </form>

  8. A First Server Round Trip Using Forms (3) • Welcome.php contains the script to process the posted data <html> <body> Welcome <?php echo $_POST["fname"]; ?>!<br /> You are <?php echo $_POST["age"]; ?> years old. </body> </html>

  9. A First Server Round Trip Using Forms (4)

  10. GET and POST (Introduction) • There are two basic ways to send data back to a Web server • We call these HTTP verbs • In all there are about 30 verbs • http://annevankesteren.nl/2007/10/http-methods • Both GET and POST send data to Web servers

  11. HTTP GET • GET sends is data through the URL itself as a query string • The URL looks something like this • http://localhost/PhpProjectDemo1/welcome.php?fname=zaphod&age=42 • <input> values appear after the ? • Data appears as key=value pairs • A & separates each key=value pair • You don’t write the URL – HTTP does!

  12. HTTP POST • The request data does not appear inside the query string • Data is sent in the HTTP header itself • It’s possible to pull this data out of the header

  13. HTTP GET and POST (Comparison) • GET • Query strings are small (100 characters) • Posted data is visible • It’s possible to bookmark the page • PUT • Large data blocks can be posted • Posted data is hidden • Page cannot be bookmarked

  14. Reading Posted Data • $_GET and $_POST retrieve data send to the server via a GET or POST, respectively • They are built-in functions • Pass the ID of the input control as an argument

  15. Example <html> <body> Welcome <?php echo $_GET["fname"]; ?>!<br /> You are <?php echo $_GET["age"]; ?> years old. </body> </html>

  16. PHP Variables • Like JavaScript, variables are ‘loosely typed’ • Variables can be declared anywhere in a PHP script • Variable names • Must begin with a letter or underscore ‘_’ character • The following characters can be letters, numbers or the underscore • Variables cannot contain spaces

  17. PHP Variables (Declaring) • Variable declarations begin with the dollar sign ‘$’, followed by the variable name • An equals sign and value follow the declaration • Examples: $userName = “joe”; $pi = 3.14;

  18. Using Numeric Variables (1) • Arithmetic operations work similarly in PHP and JavaScript • Use the $ to reference all variable names $x = 10; $y = 100; print $x + $y; /* 110 */

  19. Using Numeric Variables (2) • The following prints 10 + 100 because the value is quoted $x = 10; $y = 100; print "$x + $y";

  20. PHP Strings (Introduction) • Strings work in PHP the same way they work in other languages • There are several string functions: • http://w3schools.com/php/php_ref_string.asp • The dot (.) is the concatenation operator

  21. PHP Functions (Introduction) • PHP has built-in functions just like any language • In all, there are about 700 so we will not get to all of them • Refer to http://w3schools.com/php/default.asp for a categorized list

  22. PHP Functions (Syntax) • It all looks just about like JavaScript (except the $ notation for variables) • Functions and accept 0, 1 or many arguments • Functions and return a value • Again, the arguments are loosely typed

  23. Declaring a PHP Function (Example) • Declare a function named ShowFooter <?php function ShowFooter() { print("<br />"); print(“Rendered " . date("y-m-d")); print("<br />"); } ?>

  24. Calling a Function (Example) • Call the ShowFooter function shown previously <?phpShowFooter(); ?>